Congruence

Congruence

Lesson objectives:

• Able to identify the congruent figures

• Able to solve problems related to congruence

Open Ended

What do you observe about the figure?

Open Ended

What is special in this ferris wheel?

Open Ended

In what ways the figures are same?

Open Ended

Write the names of at least two things around you that are congruent.

Congruence in polygons

If two figures have exactly the same shape and size, they are said to be congruent.

Observe if all polygons have equal sides as well as angles

Multiple Choice

Are all triangles congruent?

symbol of congruecce

Multiple Choice

Which two polygons are congruent?

• ABCD ≅ IJKL

• ABCD ≅ EFGH

• EFGH ≅ IJKL

• All three are congruent

• ABCD ≅ JILK

Remember

• To write the statement of congruence, the corresponding vertices are written in same order

• therefore, for given two triangles, if A↔L, B↔M and C↔N then ∆ABC ≅ ∆LMN

Corresponding sides

• A pair of sides / angles that share the same relative position in congruent figures.

• corresponding sides / angles are always equal.

Symbol of Correspondence

Multiple Select

Identify the corresponding sides

• B ↔ J

• A ↔ I

• C ↔ K

• D ↔ L

• B ↔ I

Finding unknown

• Corresponding sides are always equal in congruent polygons, so if you know the measure of one side, other is also same.

• Similarly, corresponding angles are always equal in congruent polygons, so if you know the measure of one angle, other is also same.

Multiple Choice

What is the measure of ∠n in green triangle.

• 100

• 30

• not sure

• 50

Multiple Choice

What is the measure of ∠r in red triangle.

• 100

• 30

• not sure

• 50

Multiple Choice

Can you find the measure of third angle in both triangles.

• 100

• 30

• not sure

• 50

Hooray, you have learnt.

Do Q1, 2 and 3 from D2- Textbook Pg 201